A study is proposed to assess the effects of selected endocrine, behavioral and social factors on sexual functioning in older couples. Subjects will all be between 51 and 60 years older and all wives will be in the postmenopausal state. Four groups, 12 couples per group, will be followed for 6 months per couple and will include a group of long-marrieds (greater than 25 years, 1st marriage), a group of recently-marrieds (less than 2 years, 1st marriage ended by death of partner or divorce), a group whose wives have been oophorectomized and a group whose wives are on estrogen-replacement therapy. Sexual functioning will be simultaneously determined by clinical ratings based on interviews, self-ratings and a coital frequency record. Endocrine measures will include plasma estradiol and progesterone levels for the wife only and plasma testosterone and cortisol levels for both husband and wife. Behavioral measures include a battery of affect checklists and questionnaires. Social factors will be derived from a daily activities log describing all interpersonal encounters, their duration and quality. Endocrine and behavioral factors and sexual functioning will be assessed weekly for each participant; social factors, daily. A variety of multivariate statistical techniques will be used to determine the nature and extent of relationships, including multivariate regression analysis. The 4 groups will be compared both for single factors and for their respectve regression relations. The effects of aging will be obtained by comparing a group of 21-30 year olds, factor by factor and between regression relations.